Image forming apparatus such as laser beam printers (LBP) and multifunction peripherals (MFP) often include a combination of a plurality of units (functional units) prepared for respective functions. The functional units include conveyance units configured to convey sheets and fixing units configured to fix toner images onto the sheets. Each functional unit is removably inserted into a main body of the image forming apparatus so that a user can easily clear a paper jam, and when a functional unit of the image forming apparatus does not work, parts of the broken functional unit can be easily replaced. Each functional unit is electrically connected to the apparatus main body by drawer connectors that are fitting-type connectors.
The drawer connectors are provided on the functional unit side and the apparatus main body side, respectively. The drawer connectors, which have metal contacts formed in the connecters and are configured to establish energization by contact of the metal contacts, may cause chattering during insertion or removal of the functional unit. Further, when electric power is supplied to the functional unit through the drawer connectors, a large load is applied to a power supply portion on the apparatus main body side because inrush current flows through a capacitive element connected between a power supply line on the functional unit side and a ground. As a result, an overcurrent protection function of the power supply portion may be erroneously activated. In Patent Literature 1, there is described an image forming apparatus that includes, on a functional unit side, detection portions configured to detect connections in order to monitor connection states of functional units on an apparatus main body side. The image forming apparatus is configured to control electric power supply depending on detection signals of the detection portions, to thereby supply electric power to the functional units over a predetermined time so that chattering can be prevented.